History
Stale Urine as Mouthwash in Ancient Rome
Quick fact
In ancient Rome, stale urine was so valued for its ammonia content that Emperor Nero imposed a tax on its collection, a practice that persisted for centuries.
Why this is interesting
You might think of urine as a waste product, but in ancient Rome, it was a coveted ingredient for oral hygiene. How could something so unappealing become a daily mouthwash?